Particle accelerators are items commonly encountered, such as the cathode ray tubes of television sets. As with many items, however, particle accelerators occur in a variety of other applications such as scientific research, semiconductor processing, and medical imaging. Unlike a cathode ray tube, which continually produces an electron beam, many accelerators produce particle bunches. A particle bunch is a clump of particles traveling together. When produced, many particle bunches need shaping. Shaping means adjusting the bunch such as compressing it, stretching it, deflecting it, or tilting it.
FIG. 6, labeled as “prior art”, illustrates particle bunches being shaped. A particle bunch 601 is traveling from left to right when it encounters a stretcher 602 that transforms it into a stretched particle bunch 603 that is still traveling to the right. A compressor 604 then compresses the stretched particle bunch 603 into a compressed particle bunch 605. The stretcher 602 and the compressor 604 are examples of particle bunch shapers. Those practiced in the art of particle acceleration know of other manipulations, such as deflection and tilting, that are not illustrated here.
FIG. 7, labeled as “prior art” shows a rudimentary particle bunch shaper 701. The particle bunch shaper 701 is a tube 703 with a first electrode 702 on one end and a second electrode 704 on the other. The inside of the tube 703 is held in vacuum, meaning there are hardly any air molecules inside it. As such, the tube 703 is part of a vacuum system because particle bunches are usually maintained in vacuum. A voltage waveform source 705 is connected to the first electrode 702 and the second electrode 704. The voltage waveform and how the voltage waveform is synchronized with the movement of the charged particle bunches determines what the particle bunch shaper does. Different waveforms and synchronization can cause the particle bunch shaper to be a compressor, stretcher, accelerator, decelerator, tilter, or deflector. The shape of the tube and electrodes can also cause changes to particle bunch shape or other properties.
Current systems and methods cause voltage waveform sources used in particle bunch shapers to see a resistive load. The most common load is 50 ohms. A high voltage waveform source feeding into a 50 ohm load is very expensive because of the large electrical currents involved.
High power laser systems have power constraints that are similar to those of systems that manipulate charged particles. U.S. Pat. Nos. 5,754,579 and 6,914,919 disclose systems and methods for shaping high power electrical pulses. Both patents use a class of material called a nanocrystalline magnetic material. Nanocrystalline magnetic materials are discussed in detail in U.S. Pat. No. 5,591,532 and United States Patent Application 20050134515. More specifically, three nanocrystalline magnetic materials are discussed. One of them is Finemet or FeCuNbSiB. Another is Nanoperm or FeZrNbCu. A third is Hitperm or FeCoZrBCu. Other nanocrystalline magnetic materials exist. The disclosed laser systems use nanocrystalline magnetic materials for electrical pulse shaping.
There is therefore a need for systems and methods that use nanocrystalline magnetic materials for shaping charged particle bunches and thereby enable the use of less expensive high voltage waveform source.